Like many things, it depends! Best case, EV owners charge at night with off-peak rates and commute within their single charge round trip range. Worst case, high electricity use households in Southern California buy EVs and push their household consumption up in a tiered rate structure, with EV power commanding up to 45 cents per kilowatt-hour.

An internal combustion engine is fueled by gasoline, refined from crude oil at about 92% efficiency. After being trucked to your local station, and then subject to 15% vehicle efficiency, the overall efficiency is about 14%. The chart below shows the relative values of generalized figures based on a GM-EV1 and an Acura TL.

The efficiency of an electric vehicle is determined using a “wellhead to wheels” analysis. For instance, a million BTUs of primary energy drops to 390,000 BTUs after power plant losses, to 343,000 BTUs after transmission, distribution, and charging losses. Then, based on the efficiency of the battery pack and its available charge (for instance 100.6 kWh). We then apply the efficiency of the vehicle (for instance 0.19 kWh/mile) and the 33.7 kWh/gallon gasoline, to determine its equivalent mpg equivalent. The Leaf gets 100 mpg. The EV-1 got 69 mpg; the Acura 24 mpg.

Two parameters are of comparative importance: efficiency and range. The Tesla Model S Sedan is rated to travel 100 miles on its 32 kWh charge. The new Coda has an 88-mile range, the Mitsubishi i-MiEV is terrific in the efficiency department (112 miles per gallon equivalent), but has a range of only 66 miles. The Volt on-board-charging system, despite a relatively small 16.5 kWh battery pack which can drive the car for 38 miles, takes the range back to a normal auto range of 380 miles.

In related news, Lux Research reports that the EV charging will grow dramatically to a $1.2 billion market in 2020. Despite slow adoption of plug-in vehicles, the charging station market will grow in unit sales from around 120,000 in 2012 to 1.3 million units in 2020, rising from $140 million in 2012 to $1.5 billion in 2020. Europe is expected to lead the global market for EV charging with 2020 sales of 480,000 units, China growing to 277,000 in annual sales by then.

Car Talk

A green mile-marker no doubt. The Toyota Prius has become the number one selling vehicle in California, the nation’s largest vehicle market. That includes all other passenger cars, light trucks and SUVs purchased from January through September according to Auto Data Corp. Prius was 12th on the list of top-selling vehicles in the United Sates through September.

Toyota sold 46,380 hybrids in California – a quarter of all Prius sales in the United States – in nine months. Sales of the Prius family of vehicles, the standard gas-electric hybrid, the v wagon, the less expensive subcompact c and the plug-in, rose 26.3% in California.

“Sales well below expectations,” “The assembly plant taking a longer break in production than planned,” and “GM is closing down Volt production five weeks early.” “Lots of chatter, and more and more Volts on the road.”

Volts combine the efficiency of electric motors with the practicality of on-board gasoline generators. This gives them range. Volts are now selling about 2,000 – 2,500 units per month. Comparatively, Nissan is selling less than 700 of its all-electric Leafs per month.

More chatter: Reuters claimed that GM is losing $49,000 for each Volt sold. It computes that when R&D costs are amortized over reasonable sales, and added to actual manufacturing costs, each Volt costs GM $70,000 to build and sell. Today, one can purchase a Volt for $39,145 (minus $7,500 tax credit). Volt leases are even more advantageous for consumers, as little as $369 per month with no money down, a small price to pay for a $70,000 car. Worse yet for GM, in 2011 GM sold 7,671 Volts versus the projected 10,000.

President Obama test drives a Chevy Volt in 2010

Is GM really taking a blow? The automaker disputes Reuters’ estimates. It claims that its development costs will be spread over far more vehicles, with many technologies developed in the Volt used in other models. GM said the news agency incorrectly “allocated product development costs across the number of Volts sold instead of allocating across the lifetime volume of the program, which is how businesses operate.”

GM claims that it has spent about $1 billion on the car’s development, investments in research for battery cells, battery packs, controls, electric motors, regenerative braking and other technologies that GM says will be used in many current and future vehicles, further spreading development costs over a much higher volume.

GM acknowledged months ago that the Volt won’t meet its original sales projections of 45,000 vehicles in 2012. But sales are up 272% in the first seven months of 2012 from the same period in 2011 with more than 13,000 units sold. More that 2,500 units were sold in August, Volt’s best month.